NASA's Spirit completed a three-stage turn early today, the last step before a drive planned early Thursday to take the rover off its lander platform and onto martian soil for the first time.

"We are very excited about where we are today. We've just completed the exploration of our lander and we're ready to explore Mars," said Kevin Burke of NASA's Jet Propulsion Laboratory, Pasadena, Calif., leader of the engineering team that planned the rover's egress from the lander. "We are headed in a north-northwest direction. That is our exit path, and we're sitting just where we want to be."

Late tonight, mission managers at JPL plan to send the command for Spirit to drive forward 3 meters (10 feet), enough to get all six wheels onto the soil.

After the move, one of the rover's first jobs will be to locate the Sun with its panoramic camera and calculate from the Sun's position how to point its main antenna at Earth, JPL's Jennifer Trosper, mission manager, explained.

On Friday, Spirit's science team will take advantage of special possibilities presented by the European Space Agency's Mars Express orbiter flying almost directly overhead, about 300 kilometers (186 miles) high. Mars Express successfully entered orbit around Mars last month. Spirit will be looking up while Mars Express uses three instruments to look down.

"This is an historic opportunity," said Dr. Ray Arvidson of Washington University in St. Louis, deputy principal investigator for the science instruments on Spirit and on its twin Mars Exploration Rover, Opportunity. "The intent is to get observations from above and to get observations from below at the same time to do the best possible job of determining the dynamics of the atmosphere." The Mars Express observations are also expected to supplement earlier information from two NASA Mars orbiters about the surface minerals and landforms in Spirit's neighborhood within Gusev Crater.

Mars Express will be looking down with a high-resolution stereo camera, a spectrometer for identifying minerals in infrared and visible wavelengths, and another spectrometer for studying atmospheric circulation and composition. Spirit will be looking up with its panoramic camera and its infrared spectrometer.

Dr. Michael Smith of NASA's Goddard Space Flight Center, Greenbelt, Md., reported how Spirit's miniature thermal emission spectrometer can be used to assess the temperatures in Mars' atmosphere from near the planet's surface to several kilometers or miles high. Spirit's measurements are most sensitive for the lower portion of the atmosphere, while Mars Express' measurements will be most sensitive for the upper atmosphere, he said.

Spirit arrived at Mars Jan. 3 (EST and PST; Jan. 4 Universal Time) after a seven-month journey. In coming weeks and months, according to plans, it will be exploring for clues in rocks and soil to decipher whether the past environment in Gusev Crater was ever watery and possibly suitable to sustain life.

Opportunity, will reach Mars on Jan. 25 (EST and Universal Time; 9:05 p.m., Jan. 24, PST) to begin a similar examination of a site on the opposite side of the planet from Gusev Crater. As of Thursday morning, Opportunity will have flown 438 million kilometers (272 million miles) since launch and will still have 18 million kilometers (11 million miles) to go before landing.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Office of Space Science, Washington, D.C. Images and additional information about the project are available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu .